President Trump has announced his pick to replace James Comey as director of the FBI. And this didn't happen in a well-orchestrated, Rose Garden event. This happened on Twitter. The president tweeted this morning, I will be nominating Christopher A. Wray, a man of impeccable credentials, to be the new director of the FBI. Details to follow, he says. NPR's Scott Detrow is here. Good morning, Scott.

SCOTT DETROW, BYLINE: Morning, Rachel.

MARTIN: What do we know about Christopher Wray?

DETROW: Well, he was a Bush administration Department of Justice official serving as assistant attorney general during the George W. Bush administration among other positions. And before that, he had worked in the U.S. Attorney's Office in northern Georgia. More recently, interestingly, he served as New Jersey Governor Chris Christie's personal lawyer during the Bridgegate investigation. This was the scandal about closing lanes to the George Washington Bridge for political purposes that led to criminal convictions for some Christie aides but no charges for Christie himself.

MARTIN: Interesting, so we know President Trump likes to have a personal connection with people in his administration. Perhaps we can speculate it came through Chris Christie, who has said that Wray would have been a good choice for this job - Chris Wray, you know, career law enforcement.

DETROW: Yeah, and that's an interesting move because the across-the-board consensus from the Senate, who has to confirm this pick, was that they wanted a career law enforcement official in this position at this point in time. But interestingly, some of the first instincts that President Trump had was in the opposite direction. He was really interested in Texas Senator John Cornyn, former Connecticut Senator Joe Lieberman, who, of course, are politicians.

And both men actually took themselves out of the running because it was clear - it seemed like they just didn't have the support in the Senate because lawmakers from both parties really wanted a non-politician because this is a position that comes with a ton of scrutiny right now.

MARTIN: So as you mentioned, Chris Wray served in the Justice Department before. He actually served under James Comey, the man he would be replacing. James Comey, clearly not out of the headlines - he's going to be testifying on Capitol Hill tomorrow. First, though, there is testimony - big names appearing on Capitol Hill today. Who's on deck?

DETROW: Well, we have a very packed witness stand for a big hearing today in front of the Senate intelligence committee. You have the director of national intelligence, Dan Coats, NSA Director Mike Rogers, acting FBI Director Andrew McCabe - who may have a new boss, I suppose - and Deputy Attorney General Rod Rosenstein. These are all men who are in key positions when it comes to this ongoing investigation into whether there was any ties between Trump's campaign and Russia and all of the separate strains that have flowed from that.

MARTIN: Let's talk about this Washington Post piece that came out last night. They reported that President Trump asked Dan Coats, the director of national intelligence, to intervene in the - in the investigation of Russian meddling in the election. Haven't we heard reports of this earlier?

DETROW: Yeah, about a month ago, The Post reported that Trump asked Coats and Rogers, the NSA director, to publicly shoot down the idea that there was any evidence tying Trump's campaign to Russia. Both of them were on Capitol Hill shortly after that report came out. Neither of them commented on the key facts of that.

This report goes a bit further. According to The Post, this meeting happened just after Comey had said, in front of Congress, that the FBI was investigating the Trump campaign. And according to The Post, Trump asked Coats and CIA Director Mike Pompeo to stay behind after a broader meeting and started venting about the FBI investigation and essentially asked Coats if he could step in and try to slow that investigation down.

MARTIN: Let's talk about the other two witnesses today, also pretty closely tied to the Comey firing. Remind us just how they fit into this bigger picture.

DETROW: Yeah, Andrew McCabe, the last time he was on the Hill he publicly testified and contradicted the White House, which had said that the FBI had lost faith in Jim Comey. McCabe said, that's not the case at all; the FBI had full faith in Comey. So that made a lot of headlines last time. And Rosenstein, you'll recall, was the one who wrote that memo that the White House used to justify the Comey firing. He's also now in charge of overseeing the Russia investigation because Jeff Sessions had recused himself from that.

MARTIN: One last thing, the White House seems to be going on the offensive in preparation for Jim Comey's testimony.

DETROW: Yes, they are.

MARTIN: To say the least.

DETROW: And they seem to be trying to paint Comey as someone with an axe to grind, someone who's partisan and someone who has made mistakes in previous testimony. Those are all things that Kellyanne Conway said during a TV interview earlier this week. Interestingly, a PAC associated with President Trump has released an ad basically sounding like a campaign ad. I think we have time to hear it.

MARTIN: Let's listen.

(SOUNDBITE OF POLITICAL AD)

UNIDENTIFIED WOMAN: And after he testified before the U.S. Senate, Comey's own staff admitted some of his answers were flat-out wrong. James Comey, just another D.C. insider only in it for himself.

MARTIN: The stakes are high. We'll be watching all of it with Scott Detrow, NPR's Congressional correspondent. Thanks, Scott.